Marketing a developer tool is really tough (ads don't work, cold emails don't work, etc); having communities like Product Hunt and Hacker News really make it viable.
Why do you say ads don't work?
I would assume developers are much more likely to use ad blockers
They clearly do work, but at a larger scale than we're currently operating at. For smaller spends ($1000 or so), they've have a really low success rate.
Developers, specifically, tend to ignore ads (either subconsciously or via AdBlock).